Stephen III (Hungarian: István, Croatian: Stjepan, Slovak: Štefan; summer of 1147 – 4 March 1172) was King of Hungary and Croatia between 1162 and 1172.
However, his two uncles, Ladislaus and Stephen, who had joined the court of the Byzantine Empire, challenged his right to the crown.
Only six weeks after his coronation, the Byzantine Emperor Manuel I Komnenos launched an expedition against Hungary, forcing the Hungarian lords to accept Ladislaus' rule.
Stephen sought refuge in Austria, but returned and seized Pressburg (now Bratislava in Slovakia).
Ladislaus, who died on 14 January 1163, was succeeded by Stephen's younger uncle and namesake, Stephen IV, without resistance, but his rule was unpopular.
The young Stephen defeated his uncle on 19 June 1163 and expelled him from Hungary.
Stephen IV attempted to regain his throne with Emperor Manuel I's support, but the latter made peace with Stephen III.